You want a proper diagnosis before you go replacing random parts, but yes, GM has had a real lot of trouble with their front wheel bearings on their front-wheel-drive cars. The ABS wheel speed sensors develop real wimpy signals to start with. When the wheel bearing develops a little play in it, which is normal on any car, it lets the wheel speed sensor move away from the tone ring enough that the signal gets too weak for the computer to read. This even happens to new wheel bearings with as little as 15,000 miles on them. The dealers' scrap metal bins are full of these bearing assemblies.
The way to diagnose this is to drive the car with a scanner so the wheel speeds can be observed. The signal strength is also affected by speed, so the typical clue is the speed indicated for one front wheel will drop to "0" when the car is still going ten to fifteen mph. If you have the brakes applied when that happens, the computer will incorrectly think that wheel is locked up, and you will hear and feel it pulsing that brake. That is referred to as "false activation". If the computer sees that loss of speed signal when the brakes are not applied, it knows the wheel cannot be locked up. It recognizes there is some defect causing that signal loss, so it sets a diagnostic fault code, turns the system off, and turns on the yellow "ABS" warning light to tell you.
The first step is to have the diagnostic fault code read and recorded. If it refers to a loss of wheel speed signal, that wheel bearing is the common suspect. A broken sensor wire will also cause a loss of wheel speed signal, but in this case there is an electrical defect that can be detected by the computer before you even start moving the car. The warning light will turn on right away. The fault code in that case would refer to an electrical defect.
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Monday, August 7th, 2017 AT 1:49 AM
